t-case/diff swap to fix 4wd??????

[Mike621]

My 4wd is giving me trouble on my 94 XLT, and I have been told by a mechanic that it is not a problem with the hubs. The transfer case seems to have some gunk buildup around the thick gasket on it. I am not sure if it is either the transfer case or the front differential giving me trouble, but I am leaning towards the t-case because on rare occasions, when I move from being parked it tries to go into 4wd without any indicator light or such, occompanied by the whirring of 4wd but also with loud repeated banging.

I have the idea of switching components out of my 91 xl(also with the elec. 4wd) in order to fix my 94. I have little experience with drivetrain work, but I have a chilton manual and some tools. Any Ideas?

 

[glfredrick]

Before I got all the way to swapping out the t-case, I would try just changing the oil. The newer ones are really sensitive to having good-clean oil in them. My 97 has to be changed about every 8,000 in order to work right.

Make sure you use the correct auto tranny fluid - not gear oil.

The next step is to clean the electric shift motor. Do a search - that topic has been extensively covered here on the board.

Then make sure that your u-joints are not bad - test (with the truck blocked) by inserting a large screw driver into the joint - then trying to rock it. Any movement and they are bad - replace any that move. They need to be solid.

If the above stuff doesn't work, then you can start to think about a t-case swap.

 

[MrShorty]

Mechanic said it definitely wasn't a problem with the hubs, but didn't say whether or not the t-case was a problem? What was done to determine this?

1st thing I would suggest is to really determine where the problem is. System works:
1) Push button
2) t-case shift motor moves to engage t-case
3) power is sent to the front driveshaft, differenital, and axles.
4) Rotation of axleshafts causes hubs to engage.

That's basically it. Where in that flow of power is it not happening?

And, while the mechanic said the hubs are fine, the banging and hubs trying to engage out of the blue suggests to me a problem with the auto hubs. Might just be excess grease in the hubs, so if you determine the hubs are a problem, you might just try cleaning them out good, first.